Band compression television system



P. M. G. TOULON BAND COMPRESSION TELEVISION SYSTEM Feb. 25, 1958 12 Sheets-Sheet 1 Filed June 3,' 1950 /QNN www ATTORNEY.:

Feb- 25, 1958 P. M. G. TOULON BAND COMPRE'SSION TELEVISION SYSTEM 12 Sheets-Sheet 2 Filed June 3, 1950 E f e N m m u y r N m. A z f a M F F F o 0 .A M20 az n@ s@ f 5 5 5T A. .MW m/ 3 Fw PM Pw M s s SH um W L L .Lc L ar ur ar PB P6 Fd A V 2Ai| A C A a i V I l |-.,l|J m n w um FM w mf i/w f ,NM Z w .V w H n U w 2 H Il Hlll l ...Il s A L M f H A l ,v l H w s u f a M vw P Y m n u M F 2 1 .inf lllli w u r l F F M Sn .M F nu s n M Mr w. M wm m nH u P 1 0 Hv kLH /5 IC 5 C INVENTOR ATFORNEY Feb. 25, 1958 P. M. G. TouLoN 2,824,904

BAND coMpREssIoN TELEVISION SYSTEM l2 Sheets-Sheet 3 Filed June 5, 1950 NNM. V

INVENTOR o u l ATTORNEYS P. M. G. TOULON BAND COMPRESSION TELEVISION SYSTEM Feb. 25, 1958 Filed June 3, 1950 12 Sheets-Sheet 4 SMQ Feb. 25, 1958 P, M, TQULON 2,824,904

BAND COMPRESSION TELEVISION -SYSTEM Filed June 3, 195o 12 sheets-sheet 5 MULT/PLlE/ E 'I PHASE JPL/T721? C/oz INVENTOR PNG Tol/0N ATTORNEYS Feb- 25, 1958 P; M. G. TOULON BAND COMPRESSION TELEVISION SYSTEM 12 Sheets-Sheet 6 Filed June 3, 1950 INVENTOR n Pn.

FMG. Tol/0N ATTORNEYS Feb. 25, 1958 P. M. G. TOULON BAND COMPRESSION TELEVISION SYSTEM Filed une 3J 1950 12 Smets-Sheet 7 v F. M. G. TOULON BY e i a! ATTORNEYS Feb. 25, 1958 P. M. G. TOULON BAND COMPRESSION TELEVISION SYSTEM Flled June s, 195o l L75 "we INVENTOR F? f7 7ULO/v 'm/wW/ ATTORNEY Feb. 25, 1958 P, M, G, TOULON 2,824,904

BAND COMPRESSION TELEVISION SYSTEM Filed June 5, 1950 12 Sheets-Sheet 9 F16. lo.

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I S m@ E N 2 Flan' l 21S l59- |47 |201 m miJ d twv/'20 3 S@ W wf-'20 SS@ www@ 3 S sev-v T T 'L .g 59"*L@f"1m1 --120u 159m/ TW/mom 4S m @WW2-Mom 4. S fm^ f r-l20m` @ffWP-'ZOI m 89""1 'E 'L T. I{ 5 @n l I w@ FIG. l5. 5' iS/(Qi q INVENTOR R M G. TOULON ATTORNEYS Feb. 25, 1958 P. M. G. TOULON v2,824,904

BAND COR/PRESSION TELEVISION SYSTEM v Filed June 5, 195C l2 Sheets-Shea*l 1Q FIG. I3.

(End Of Line Signals 23 End Of Frame-2 INVENTOR FIG. l5.

R M. G. TOULON BY @7m l #42 ATTORNEYS Feb. 25, 1958 P. M. G. TOULON BAND COMPRESSION TELEVISION SYSTEM 12 Smets-sheet 11 Filed June 3, 1950 NVENTOR P. M. G. TOULON BY @www Z /L-Qi ATTORNEYS Feb. 25, 1958 P. M. G. TOULoN M 2,824,904

BAND COMPRESSION TELEVISION SYSTEM Filed June 3, 1950 12 Sheets-Sheet 12 Differences M-N INVENTOR ATTORNEYS Y COMPRESSION TELEVISION SYSTEM Pierre Marie `Gabriel Toulon, New York, N. Y., assignor, by mesne assignments, to Moore and Hall, Washington, DfV C a Parmership This invention relates to'transmission systems and `more-particularlyto apparatus for sending intelligence from one point to another with reduced bandwidth. The

Ainvention may be used to send television signals or color television signals with reduced bandwidth.

-A primary object of this invention resides in the provision of a practical system for transmitting intelligence from one place to another with reduced bandwidth. Another object is to provide improvements in such a systern to effect low cost.` Other objects will appear as this description proceeds.

Although the number of points scanned in each station remains ythe same, it is still possible to reduce the required number of informations through the cable (or example a-coaxial one) connecting the two stations. The invention when applied to television is based upon the optical property ofthe eye which requires a high accurate iiickerless deiinition as long as the picture is not moving, but tolerates a-low definition when the picture is rapidly changing.V In the process according to the invention when the ipicture isfnot moving, the same intelligence ,once transmitted is used successively as often as for instance ve times. VTherefore a great nesse is obtained without dicker. At the points where the picture is changing, an automatic enlargement of the point is realized momen.- tarily so as to give immediately a coarse indication of thenew aspect of the changing part of the picture.

A picture of 525 horizontal lines, each line having 500 points at 60 frameV interlaced scanning requires 7,800,000 values of voltage in the channel and consequently a bandwidth of more than 3.5 megacycles. lIt is wellY known that it is extremely difficult to transmit color within that bandwidth, unless some special device is provided.

vAccording to the invention the number of intelligence signals is reduced up to tor' instance, five times, so that a band lower than for instance three megacycles is suicient to produce the same apparent result for color and resolution. The invention uses an'autornatic process of repetition of the points while the picture is not changing and provides an automatic enlargement of the point while the picture is changing.

The invention may use the dot interlaced technique, or knights move technique such as described in my U. S. Patent 2,479,880 of August 24, 1949, in which the total surface of the screen is divided in a great numberA of checkerboard cases, each case having the same number of points.

One form of the invention which has a bandwidth of States rice e Five recordsof the tive successive eld scannings are made successively at the receiving terminal of the cable, in ive'separate magnetic recorders. Each record is read again through an independent reading deviceand resulting currents are supplied in tivev distinct channels. These ve channels are sampled to 'locally rebuilda new highdenition vvideo intelligence current that is practically the samev as the initial high definition video intelligence for the eye of the observer. When the televised subject is not moving, the reading of each record is made tive times, and the new high deuition channel uses five times the sameV indication in the course of ve successive field scannings. Consequently the information'required to be transmitted through the cable is tive times less thanin the classical transmission process. The-beam jscanningfrequency at the receiver remains the same as `now used, namelyf2 30 per second in the line interlacedmethod. Consequently if the subject is not moving, a veryiin'efpictureappears onthe screen in spite of the low rate ot' intelligence transmission.

When the -sbject is moving, a switching device is actuated with the Ipurpose of spreading the voltage` value of the lastlield-point value to as many as live consecutive points ot picture. V

According to an``ernbodirnent of the invention for operating saidswitching device the successive values of the recorded intelligenc'e'fior each'dot of the picture are com- "pared onfewith the-"other explored at a time spacingof 'five elds. When asubstantial change is noticed by the comparing device, the new value of density is automati- 'cally applied to the receiver output. This new value is vapplied to the two preceding and the two following dot "locations along the same line. Each magnetic recorder and eachmagnetic reader,

' abovev described, inV this system are required to be operated at the maximum Vband capacity of the cable, for 'instance three megacycles One alternate means of the invention provides the useof cathode ray memory tubes 'for recording and Vreading the intelligence.- In accordance with the described means relating to]magneticV re- 'corders Vthe Vinertia limitations of said means lead to provide a multiplicity of such recorder and reader combinations each operating at their maximum limit ofuse- :ful frequency which is only a small fraction of that of the cable. -A high speed pulse distribution system 'as described in my Patent 2,471,253 is yusedv for thespurpose of distributing the successive pulses of video intelligence to the multiplicity of magnetic recorders working simultaneously each on a fraction of the total intelligence. `The pulses generated by the reader head of the magnetic Vrecorder are sampled with a second high speed one-fifth that of a conventional system will nowV be very briey described. During the rst scanning of an area only one-fthrof the spots are transmitted, and during the next scanning another series of spots which comprise onefth offthe total are transmitted. This process is vrepeated forpfve-scannings at which time allspots will have fbeeri;i scanned and theinformation'sentgover the connecting, ca ble to the receiving terminal of the cable.

distributing system used to combine the pulses i into linal videointelligence channel Vfor local retransmission to the home television receivers. l

In order to make the recording easier, a high frequency modulating device is provided for actuating each individual channel of each recorder. These modulating devices are supplied through a common heterodyne.

Means for erasingtherecording are provided aheadof the recording and reading device.

In the drawings: Figure 1 is a simplied showing of the systemand-has two parts, Figure 1A being the originating station and Figure 1B-being the receiving (relaying) station.

Figure 2 shows curves of the voltages involved at the transmitting station.

Figures 3A and 3B form a more complete illustration of thereceiving station of Figure 1B. f ,FigureA illustrates an electronic switch thatA may re-` place Ysvvitchdili` ofiFigure 3. I i L Fiure'S illustrated an electronic Vswitch Vthat may-'be used'as the comparison circuit .3750

Y 'delay lines of Figures 1A and 3. Y n

`certain potentials on certain wiresY of Figure 6.

' Y dot system.

356 ofFigure 3. .Y Y j Y Y Y Figure 6 illustrates the circuit of the knight movel Figure-6A illustrates Figure 7 showsV the face of fav'cathode ray Y'tuberandr anY order ofVY scanning th ,interlaced system is used.

FiguresV 8, 8A and 8B illustrated details of the recorder Y Y Y 1o 111 and 112. f'DuringY the period yofgw'aye-104A, fthe usef ful signals appearV above line VC-i-Cand areA spaced by j two units from the beginning ofjpenod Vv1014A.)vr This spac-*Y Y ing is caused by delay line 11,0.betweenpoints'A `lllgandg'.V V113.*fl'hejresultv of Vall of the useful-'signals Yi'sfshown Vin f line D of'Figure 2.3 Assuming interlaced scanning, the; Y

of FiguresjlB and`r3.

. Figure 9 shows an electronic-switchthatmay replace Y. switch320`Y (and similar switches) of Figure 3; Y QAiIIuStrates-certain details of Figure 9.

K Figure `Y `Figure. `Ylillustrates the scanning` whenfthe tive 'dot system is used.V

together` with relayYV ereon, when t he three dotnon n Figures;Y lljand l2`V illustrate the order of scanningYof the ycheckerboard.` 'Y Y Y Y VFigure `1,3 'illustrates aftrans systemisemployed. Y f Y Y A *Y Y t v Y Figurel4 illustrates a system of controllinginformaber of unitsv downrthe picture is assumed lto be ten.Y} Y

tion to'be recorded and convectedetorthejoutputfof Figure 9-Yi Y Y Figure 1 5 shows'a switching system useful 'inthe ive dotsystem. Y n.

Figure l6'ris a circuit of an alternate form of aV fine :Figure .17.isY ai' chartof certain voltages appearing in the ve dot system.Y

- FigurelS shows YcertainYwaveforxns ekplanatoryfofra YFigureg9. Y Y YY The inventionvlwill first be described withfrerference tol-a system requiring'Y only one-third of the usual bandwidth. Latera system requiring onlyYY one-fifth` of the `usual bandwidth is describe ,Y Y Y Y Referring first toFigure l,V the sub-Figure V1AY illustrates theoriginating station ,whichV is connected'by a long line (or'radio link) with thesecond-ordeciphering station of sub-Figure -115, `The details of Figure 1B-will be explained with reference to seyeralrnore detailed figures. Y fl -v 11n, 'Figure lA the usual'siXty-cycle'per second 'power y,line feeds motor-generator. 100 having a ten Vcycle per second three phase output- Lirniters 101 limit the'output Vto three rectangular Wat/ es YAA, B', VC (see Figure Y2). l'heserectangular Vwaves do not overlap, but appear suc-'- cessively'in time.r During the period of wave 102A, theY `second grid of,tube102 opens this tube to admitcurrent .Y How, buttubes 103 and '104 areYnon-conducting. ;V Similarly during the period Vof Vwave'103A only tube 103 Vhas Vits lefthand grid Yenerrgized-,vand durin'gthe period'Yof" wave 104A jonlyYtube 104 has itsrlefthandV gridV energized. As usually, the Yend of' frame signals and end of line signalsar'e generated separately and synchronisedv on .the classical 60V. A.VC. ,l f Y Y YY Video camera S produces video signals across ,wires Y 106..Y The end Vof line signalsYarr-iving on wire 107, are multiplied in multiplier'lS and are then fed to Y i pulses; generator V109 and lock theV latterrinl synchronisrn therewith. The output repetitionrate'ofpulse'generator more thangthose reachingll-Twhich in turn are delayed` vonegunit more than-those at 111.VY This will be'explained g letterYA of Figure 2.1 Likewis e"theV signals arrivingat,Y j, Y point 112 and fed by wire B?. tombe-103 areV designated Yby letter B of Figure' 2.v YSimilarly the-*signalsarriving.

Y section magnetic (recorder.

thesersig'nals adjoins the'starting axis Y-Y.' TheY o therV useful signals of thisV group Yarerspa'ced from each other ,Y by two interveningspaces. VConsequently these signals, Y open the second grid of Vtube 115 only during the crosshatched portions of curve 114,v ADuring' the period of wave 103A, the useful signalsv are shownin'line Bfi-B' and `it-V is noted that there isrjacnne unit spacebetween j the beginning/oi period 103A and Vthe firstV useful 'signalg This delay isV caused by'l the zdeIay-line'Y 11.0 between points sequence of spots scanned during Athe period of onecycle'fl i of generator 100 is shown in Figure 7, except for purf -across the picture Visassumedtofbeffteen and-the @nurn- Slithrough 75 duringithe period of waveYY104A`. `'Die result'is thattube 1715 hasA anfoutp'ut. ofVK pulses. Each pulses respectively represent spots Vin 1the;sequen`ce of Figure 7. Since the space.betweenspots.istwo units,

clearly the repetitionjrate of the'outputsignal isonlyVVV one third ofthe conventional output; Y

scannings VVtoV fp'ictujre. Y -Y "Referring there will be disclosed. areceiver for Vsuch scanning.IV `In FigureY 1B, signal distributor 2004r'nakes one revolution for eachentire' picture and sends the signals emitted Y during period 102A to recordersection 201 `of a three During period 103A Vthe 'switch 200-sends'thetransinitted' signals torecorder secV Ytion V202, and vduringlperiod V104A5the swtchf200 Vsends thetransmitted'signalsY torecorder section 203.

p 201A picks off'signalsapplied by-hea'd, Y201. yLikewise Ypickups 202A and 2,03AYr'espectively pickrfupY the signals A' 109 isrone third of the numberofdots in a line. TheY Y' Y output-pulsesofpulse'generator109 are fedinto'delay line 110.Y Pulses reachingkpoint 11,3Yare delayed one unit' i at point 113 and fed by wire C? totube '104'ar`e' designated by letterfC"`of'Figure'2. Eachof-the tubes 102,"1103` v Y andz104 is so constructed and, arranged that it will pass 'e current only when both grids are/energized.`V Asa result ,r ,Y a during the period ofawavelQZA; 'thelpuseful signalsV are'v 7 5 recorded Vby heads -202'and V203. *More details'y off the recorder will appear in connection with Figuresv 3Yar1dY8.Y Y

Referring now Yto YFiguref7,`rit is clear `that. vthel signal Y representing spot Y1 isithelirst signal picked up by pick-.up Y

spot'Y26i is -lhe rs't signal 201A; The signal representing picked up by pick-up 202A, andY the signal representing The signal representingspot 2 is thesecond signal; picked upbyfpicklup 7201A. A'1`vhe refo`re,A since switch 204 makes*Y Y Y one revolution/for every threedo'ts,fit reproduces the'dotsVY in Yits output circuit in v'theiYfollovi/ing sequence1`\2,6,-"51\,

:Hence theoutput'leadi horizontalV .lineV shown? other' horizontal linesg'; Y, t Y` YHence, wliilfdo't`s"Y re'skippedfduring transmission.;they` have now been restored; ,If-thepicture'isno'tmoving'the,

`Youtput of'swi'tch 204 `will gipve'jtrueA reproduction of the f picture.` IfYthe Ypicture is moving/some modicationliri 'Y a the outputis desirable -andi'to provide this inodil''c'ation,Y switch 205jr`otates 'synchronously withY'switch-f200 and removesYa series of pulse" signals pick-upsY 201A,-r

. etc.;

pose'of simplilcation ofdescription the nlluiber-VoffuimitsV vSo far as the 'draftsniansr'notes on FigureYV land the n accompanying description arefconcerne'd, the AterinWenrtire'picture refers Yto a'scanning that senseslevery third.v

. dot of the' whole pictre, hence it AwouldY'take three such develop 'one signalV for each dotvof Y'the now to 'Figure"lB, it will be assumed, for `V sake' of simplicity, that interlacedV scanning is not employed,` but later in connection with FiguresA; andBB VYAfter the recorder hasrmade one revolution the pick#Y Aon recorder 321.

202A and 203A. The signal output of switchr205 is the same'as the signal that was fed to' switch 200 at atme preceding equal to thel time of three entire pictures. Therefore, the output signals of lswitch 205wwill be duplicates of the input signals of switch 200 if theV picture is not moving. Under these circumstances, if the comparison circuit 206 indicates that the signals are the same, relay coil 207 is not energized and Varmature 208 connects switch 204 to output lead 209. If the comparison circuit 206 indicates any dierence between the signals on lines 205 and 210, the relay coil 207 is energized and the signal on line 210 is fed to ouput 209.

Each of the mechanical switches and relays may be replaced by well known electrical equivalent electronic circuits to perform the same results. Before discussing possible electronic circuits, a more detailed form of the receiving station (shown in Figures 3A and 3B) will be discussed. The receiving station of Figures 3A and 3B is a three-dot system and is adapted to decipher the output of Figure 1A. Y Y

In Figure 3A synchronous motor 303 makes one revolution for each frame (one each tenth of one second)v and rotates switches 304 and 308 at that speed. Motor 303 is controlled by synchronizing signal line 301 which in turn obtains control signals from terminal box 300. Switch arm 305 is geared to switch arm 304 and rotates at half the speed of switch arm 304.

Input lead 302 carries the video-signals and feeds switch arm 305. Switch arm 305 contacts element 306 during .scanning of one complete frame of the picture and contacts element 307 during scanning of the next comf plete frame of the picture. Switch 304 causes the impulses representing the first picture to be recorded on recorder 321 and switch 308 causes the impulses representing the second complete picture to be recorded on recorder 322. During the period thatswitch arm 304 contacts member 310 (during alternate revolutions) the pulses from spots 1, 2, 3, 4, 5, 6 etc. (of Figure 7.) are transmitted to switch arm 315 until every third dot of the picture has been sent. Ify we assume a picture with 300 picture elements on each line (instead of the iifteen shown in Fig. 7), then switch 315 must have 100 stationary contact points on its periphery, and each sta'- tionary contact feeds a separate recording head 315H After every third dot of each odd horizontal line is recorded by switch 315, switch arm 304 moves to contact element 311 during the period of transmission of the second, fth, eighth, eleventh,vetc. dots ofeach horizontal line. In the illustration of Figure 7, the switch 316 would cause spots 26, 27, 28, 29, 30,31, 32V 36, 37 41, 42 etc. to be sent to recording head 316H. Switches 316, 317, 318, 319 and 320 are all identical to switch 315 and to each other. They may all be electronic switches if desired, and Figure 9 shows a suitable electronic switch to replace these. Reverting back to switch 316 it has 100 contactors which supply 100 recording heads 316H disposed along recorder 321. In like manner when switch arm 309 is contacted by arm 304 and the remaining dots of the horizontal lines are sent to switch arm 317 `which sends them to 100 separate recorder heads 317H. During the time required for the various recordings on recorder 321, the recorder makes 3 revolutions, and no further recordings are made on the recorder 321 until after the. next complete picture is recorded on recorder 322.

After the data for the first picture is recorded, switches 308, 318, 319, and 320 proceed to record all of the data for the second complete picture in the same way that their complementary switches 304, 315, 316, and 317 recorded the data for the rst complete picture lines. When this has been done it is clear that the recorder has one recording for each possible picture element and will have a true representation of the picture if it beY :issumed that the picture was not moving.

4 The pick-up heads are shownon the 'hand sides:-

ff`"""""" i 6 'i l' 'i ijf. of 'recorders'321 and 322 for purposes of illustration only. In fact, I use a common head to record and to pick-up data. This canwork for the following reason. The first picture is recorded on drum 321. The second picture is then recorded on drum 322 and during this recording there is no recording made on drum 321 but the switches 323, 324, 325, 340, 332, are in such position to feed oi any signal picked-up from recorder 321. Hence, when a signal is being recorded on one of recorders 321 or 322 the other one is free for pick-up operations. After each pick-up operation an erasing means (not shown) is caused to operate by appropriate switches to eraserthe recorder. One Vcomplete frame after a recording by head 315H the recording is picked up by complementary head 323H and routed through switch 323 to contactor 337. The same is true for all of the recordings thatpassed switch 315. The recordings made by switches 315, 316, 317, 318, 319 and 320 are all picked-up one complete frame later and are respectively routed by switches 323, 324,325, 326, 327 and 328. The recordings routed by these switches are-respectively sent to switch contactors 337,338, 339, 353, 354 and 355. During scanning of even numbered pictures (second, fourth, etc.) switch arm 351 connects line 388 to switch arm 340 and during scanning of odd-numbered pictures (first, third, etc.) switch armi351 connects line 388 to switch arm 352. Switch arm 351'rotates at the same speed as switch arm' 305 and as a result the signals fed to line 388 are identical to t thoseY fed one complete frame earlier into switch arm 305. The comparison circuit 350 compares the signals'in line 388 which represent one frame with those in line 389 which represent'signals transmitted at one complete frame thereafter. If the comparison circuitindicates no change in the signals, the relay coil 356 is not energized and the recorded signals are delivered to the output. If on the other hand, the comparison circuit 350 indicates a change, the relay coil 356 attracts the armature and connects the line 302 tothe output circuit.

-It is'observed that switches 332 and 336 makeV one revolution for every three dots or units. It will appear from Figure 7 that to produce the'v first horizontal line it is necessary tol scan dots l, 26, 51, 2, 52 etc'. inthat'order. Dots 1,'"2, 3 etc. appear successively oncontactor 329'. Dots 26, 27 etc. appear on contactor 330, and dots 5l, 52 etc. appear on contactor 331. TheY requirement is .therefore to select dots sequentially from these three con'tacfy tors. VSwitch arm 332 which makes one revolution every three dots does just that and produces a pulse output' with pulses in the sequences shown by lthe horizontal lines 'of Figure 7, except of course there are'300 horizontal dots in each line instead of fifteen as shown in Figure 7. Likewise switch arm 336 which cooperates'with contactor's` 333, 334 and 335 produces a pulseoutput for the Yeven horizontal lines. Switch arm'357 makes one revolution, for each two complete frames and is in -contact'wit'hfcron-V' tactor 358 while odd numbered pictures are being scanned' and is in contact with contactor 359 during scanning of even numbered pictures. Therefore,'the`switch arm 357 receives a complete picture of interlaced scanning but dis-V placed one complete picture in time. When, therefore, relay coil is not energized, the picture sent to the output'is a complete one in every respect of the still object being televised. When the picture is moving, therelay coil is energized from time to time and modifies the still picture..

When a picture is still the eye requires a nereproduc-ition otherwise the picture will appear incomplete.Y When the picture is moving the eye requires much less detailin the reproduction and the coarse signalfed over line 3024 (equivalent of the wire 210, Fig. l) is quitesuicient. .The

reproduction can be improved if a delay-line 360is itibefore it appears to occur. The relay coil356 may, if

desired, have a lag of one or more dots so as to cut off Y al1 signals coming through-fline360 as long as theipicY Y fr connected toy theroutputl and be triggered by'ili'nef302 `to Agsupply' two Vmoredo'tsto the output when the relaygr36'1 is down. Y. j Y n .Y Figure 4 illustrates Ian electronic switchto replaceme- Vclianicalswitch 332, and asimilar switch-may'fof course Y Y Yaser,'soft Y and cause the Vlatter-to oscillateata frequency ofone-hgalf i Y the Vrepetition rate offthevend f'li'ne signals?l 'Y The out'a l,

'purer escalator 6011s fed info phase splinerrandlinifer j 602=whichy produeesa two'phase rectified'output `she'wi'r 1 in Fgure^6A.-- Theyrepetition rate of .thef pulses'inpwir'e'f l603i is onepulse for every other linefaTheis'nie may' bel( replacerriechanical switch 336.`Y In Figure 4 an oscillator Y 400. has its frequency controlled by Vsynchronizing;signal y 301 Yand oscillateseat a 'frequency o f one Y'cycle for every K Vthree dots; Phase.splitterllliconvertsrthe Vsinglevpharse 1 Y to three phase and the latter*isrectified'in rectiiers 4 02 Y `andjirnpressed'across @resistors 403. 'The' rectiiie'd half wave threep'hase" is thenfpass'edfinto` limiter-404ito` prol Yduce the square waveroutputforrnsl308ghaving nonover lapping-rectangular pulses.=V YThis can/beaccornplish'ed by selecting the 'proper degree of limiting action. Tubes 405,V

' will connectto the return lead from fthe pick-upl head n 406 and407Y are non-conductors Yuntiltheir second grids Y receiveY a positiveY impulse. 4Hence, the1tubes`405g406 and 407-are activated sequentially by the rectangular pulses. Therefore 'the' circuit sequentially connectsfleads f 329A, Y330i5lffand 331AV to output leadf332 A. The last Y four leadsmentioned correspond to similarly marked leads onFigureB.

" When it is desired to use Velectron'ice'switching in placeY of relay356,the-comparisoneircuit and the relay coil can take the form shown in Figure 5'." Input 388jof Figure 5 Vis wire388 of YFigure'l y3V and inputwire389 is wire 389 of Figure 3. Output wire362 of FigureS is the correspond-Y ing wire of Figure'3. ,Input signals Y388 and 389.are `applied to the Vgrids of tubes 90l and 91; Y The plates of these Vtubes are connected to resistor'sl90R andV V91"R. These'resistors are variable in order. to aid in balancing the circuits so that when a still picture is televised the outputs Vof tubesv90V and 91 willbe equal.v YThese ouputsare applied across fullV u Vwa'vefrectitier 92 so that if rthere is any difference between Y j the .outputs of4 90V and "91, Va potential willrappear across condenser 93 and resistor 94. An oscillator 95 generates a high frequency carrier wave'which is impressed on sec'-A ndary 96. In the absence of potentialracross resistor 94 theV secondV grid of tube 100 is biased'p'ositive by battery B whereas the second grid of tube 100 Vis not biased. Thisy causes tube 100 to become conductive and to be triggered bythe signal from Vline 388; Hence, the output online 362 is controlledin accordance with the output vof the recorder. When inputs 388 and 389 differ, a; potential ap- Ypearsacross resistor 94 which addsrtoV that on secondary 96 and battery'99 and causes Ycurrent iiow inrectier '97. Y

This current passes through the primary of transformer 98 `and sets up vtwo secondary currents which are both rectied and one of which biases tube100 to cut-off and the Y other of which biases the second grid of tube 101 so' it will vbe controlledaccording tothe variations on its first grid.

Therefore, variations on lineV 1389 will control the rst grid on tubel 101 which willin turn produce variations in line Y362V according'to those on line 389. An appropriate g output amplifier 102 may be employed. L

T he'foregoing discussion hasV ignoredY the knight move L delay line found in both the sending and receiving station;

` betrue knight` moves and the .other'half otherwise. Y

The knight move4 delayvlines of Figures lArand Y3B- are identical 'and are triggered'by end of .line signals.

The circuit of such aY delay line is so. arranged that every otherV fend of the line signal. places the delay circuit in operation anddel'ays the signal a small amount, whereas the intervening end of line signals docause less if'an'y,

' signal delay. .Figure `6 illustrates theircuit for the knight niov'edelay lines. f j Y f Figure, end of line lsignalsltll) feed oseillator601 Vconnect-to switch arm 351 inthe case of knightatrioye,fv

fof Figure 6Y is -appliedfto.Figure1A, input wires/anfd if 666 of Figure 6 may connect Vacros's'resistor 186'ofFi'gre 1A, and'wirre 600 'of Figure 6jcon`rnect to' wired/07 and to Y v v ground'respectively of FigureflA. V'The outpntlzeadsA Y' Y Y and 608 of IFigure 6 are applied to the'second-'grid'to cath-V ode circuit of Figure 15A.-* InFigure 3B,l Vthe output leadsVv V607 and 608 of knightfmove 396 feed amplifier .399,1

and the output'leads of knight moveY-397 feeds delay Y line 36o.

" lIn `Figure 6v each of thettwotubes isnon-j conducting except when receiving'apulselon its'secondgVY grid. 1 During the period of a pulse on wire V603,1tube 609k 'A A is Yconducting Yand'tube non-conducting. During thisVV period the incomingrsignals on wires 605 -andf6i6-enY counter only the first sectionv of delay line 611 and hence are delayed'onlyV slightly. Duringthe period of energy .Q on wire 604,'only tube6101coductsand' thisfcauses ltlileV i energy on input 605, 606, to havea two 'stage' delay bef fore lreaching the grid of tube"610. Hence, if we assume` Vinterlaced scanning, duringthe scanningY of line 1,1tube 5 `Y Y 610 will be open' and .onlyY a` small delayA will be er1-i countered. Due to'interlaced scanning,'lir1e Zwillfhe. skipped and hence'line3`will Ireixt'be scanne'dkAllof the dots on fline 3,'will; howeverrbe displaced to theu'rig'ht;as'A .Y E

compared to those on' line 1,vdueto'the full effectofidelay i line 611; Hence, on alternate linesVj scanned :'compliQ-j* K nientary dots will be displaced'from, each other instead of being in vertical lines. i j l i Y 'Y Figure 8 shows details ofthe recorder." A base53 of heavy stockrsupports synchronous motor 52' which Vdrives f 45; shaft 57 that is arranged `for very accurate rotary motion with bearing jsupported by fframer54. Thels'mooth accurately machined cylinder 51j' of magnetizable 'rua-sY Vterial and suitable for Vstorage. of signals Vis rotatedf'by Y shaft 57 and constitutes the recordingfsurfae; 'VIhe recording heads H1,.H2, H3, etc. `are disposed around 'the Y' peripheryV of the cylinder,A but since their s'up'pcrtuSSiis` Y inthe form of ahelix ther heads are actually spaced short Y distances axially along `,the cylinder. The resultis' that a. large 'number 'of/recording"'headsV can` operate on `a single cylinder without interference.

view. g The right hand' recorder clearly'shows thefhelical arrangement 58 of the recording heads; Figures V8`Afa'ndYV i Y Y n The left-handrecorderV of Figure V'Sais shown as a sectional viewwhereasV the right-hand'recorder'of Figure/8 is shown as ajfsidej ,n

8B show details of fthe recording apparatus,V rfE-Chjrel-g Y cording Vhead has Vthe usual Vmagnetic circuitfand'coilfj Af suitable recorder "i is' Vshown in my priorPratentf Y 2,471,253. Y 1 Y,Figure 9 illustrates an electronic circuit which will rre-"e` place any one `or incre;ofswitches.315vto 3720 or3'23 to Y "328. Line'60 YofrFigure 9 isjconnected'toisynchronizing 'Y signal. wirel 301jand excitestwof'osillators 61and.62 i

whichrespectively have frequencies andprCFrwlierey F' is-fa common; basiejfrequency; 'Each oscillator,hasanY output-'5in phase quadraturewithenother of its outputs.' f Y *u For example oscillator 61 furnishesV line 61A'Qwith volteV Y age in phase quadrature'with'the lveltagein 'line`61B, all'k Yat frequency KF.` Likewise ,oscillator62 furnishes. line' 62A with voltage in phasegquadrature .toV thati in line" the primary of 'transformer 900. Likewise line 61B feeds the primary of transformer 900. Likewise line 61B feeds transformer 901, line 62A feeds transformer 902, and line 62B feeds transformer 903. Each transformer has 100 secondary windings only four of which are shown. The phase of the voltage on terminal 904 depends on the amplitude and phases of the voltages on the four secondaries 63, 64, 65 and 66. Likewise the phase of the potential on terminal 905 depends on the potential andphases of the four transformers that feed it. Since vswitch `320 has 100 output ,leadsv successively energized, -it is obvious that there shouldV be 100 secondaries on each transformer of Figure 9A.' The numbers of turns on the several windings in each circuit are so related that the voltagesrin'thevlOO 'leads rise to'their peaks in given sequence and so that the process repeats itself with the rst output reaching its peak in sequence after the one-hundredth one reaches its peak. Each output lead (such as 904 for example) has -biased rectifers to act as limiters and thus produce pulsed outputs for those portions-in excess of the bias of the limiters. Assuming this bias to benear the peak value'of the voltage wave, the outputs will be discrete pulses not overlapping in time.

The .upper ends of the secondary windings of transformer 900 are all interconnected. To complete the first circuit 904 there is a connection through the 50th transformer as shown as 63', 64', 65', 66', 68', 72', 73. The

potential outputs of the circuit having both of these transformer groups combines and is fed to the top end of, resistor 74. OnceV each cycle, therefore the rectifiers 75, 76, 81 and S2 are caused to conduct from input 59 to. output 843. Output 84 leads to one recording head. Y Out-V put 85 leads to the next recording Vhead and so on until,

quentially, and those 100 circuits trigger 100 output circuits in sequence to connect the input to the output. Vacuum tubes with grids may be substituted for the :rectifers of Figure 9, and in this case leads such as 73A lwould trigger the grids tV connect the input (cathode) :to the output (anode) in the Well known way. .A

Figure l0 shows a checkerboard arrangement of theV :scanning dots for a ve-dot system. l In thi'ssystem onlyv one of every five dots is transmitted instead of one of every Vthree as in the case of Figure 1. In Figure 10 the 'whole checkerboard is divided into smaller checkerboards of twenty-squares each. Figures V11 and l2 show the order of scanningl of eachv ofthe checkerboards.

Moreover the numbers'on'the squares in Figure l0 showr the order of scanning with the primed numbers showing the order during interlaced scanning sweeps.

For the particular application, I use preferably a knights move dot interlaced scanning as described in my. Patent 2,479,880; according to the invention the` points of the picture are divided in a certain number of checker groups for example Y Y in vertical direction and for instance in the horizontal direction. As described in Figure each checker group comprises for instance 4 points in the Vertical direction and 5 in the horizontal direction.

Thepreferred order of exploration is described below in ten successive fields as shown in Fig. 1l and afterV which the cycle begins again.

The rst scanning of screen odd lines uses all the points marked'l in the rst location in the rst line, all

ofn the points marked 1 on the third line and so on alter,r nately for all the odd lines of the first field.

The second scanning of screen, even lines, uses the third location of the fourth line for point 1' andalterfv nately for all the lines` of the even numbered field.

The third scanning of the screen odd field, odd lines uses for points numbered 2 at the fourth location at line one andthe fifthlocation at line three and so on alternately for rall odd'lines of the third field. f

The fourth scanning of the screen 'even lines uses point numbered 2 atjjthe first location of theV second line and the'sec'ond location of the 4th Vline and 'soion alternately Y for`all`odd'linesofthe'fourth field. And'so onas shown inFigures 10 and .11.1, l

`In this fashionV tensuccessivescannings of the screen are required to cover. all thev points of the screen. According to. the classical standardsfa 2 Sinterla`ced line scanning is' usedso the respective positions of the points are Avisible?irrFigure `2.' It appears that 'a time Vof! 1%)'='% of secondilapsesA between" two 'successive sam` plings ateach point of thefhigh definition picture. Accord-V ing to ,the invention onlyfthelpoints chosen for sampling are :transmittedinfa greatly reduced number.

Asl a result this' 'new"scanning' process requires only' the transmission l, the number usually sampled that will be about 1,500,000 video signals per second. For the transmission of color it appears that a 3 megacycle band width of the coaxial cable is largely sufficient to retain bothV high definition and correct coloring of the picture,- athing which is impossible with the band width now" in use.

The -invention .hvasrthel property of rebuilding at each,v station, a v ideo classical channel of highV fidelity that does; not much differ'from 'the initial intelligence ofthe elec-j' trom'c'camera Vat thefinitrial stationnand ready to b e local-g ly retransmitted to homevreceivers. l

In Figure 13207is the high V,definition ,electronc camera, 22 the channel for theend of line signal, 23 theV channel for end of image signalf 21 thevideo channel.

As we observe the frame of Figure l0, the order of the' thirdline 413,52 is shifted by one unit in the order of the rst line 13524. In order toobtain this phase shift after'y the end of eachline the invention provides two tubes25vd and 26 alternately operated through oscillator 27 syn-A chronized on half frequency of the end of line signal?,4 received through the channel 22. Theseltubes have two control grids. The frstgrid being 'connectedl to different terminals of artificial line 24 and the second grid is biased or unbiased at the frequency of oscillator 27.

The plates of the two tubes are connected in parallel` and to wire 28. Y. t

In order to modify the order of the points toV `be scanned, in the following fields, a second artificial line 29 is provided. The delay'line" 29 supplies the first grid of abank of tubes 30,31, 32, 33, 34. The second grids. of this bank oftubes areA normally biased or locked andthey are successively funlocked at the frequencyrof the` successive fields througli'the meansof a commutator 36 d driven through a small motor 37' synchronizedin 23 so that one turn corresponds toten successive fields. lThe plates of the tubes are connected in parallel. Consequentlyfor eachfield only `one of-,theV tubesv30 to 34is unlocked supplying the output resistor 35 with successive voltages corresponding to the chosen order.

A further improvement in the invention providesfaccurate constant values for each successive point through the means of tubes 39 and 40. In order to facilitate the transmission vof the video signals through Vthe 'narrowf band coaxial tube, vit is highly desirable that the individual values successively sampledon channel 35 are Vnot `sep: arated but are connected 011e to the'other without periodic interruptions. .For `this purpose,'1 providetheruse' ofY tube V39 to' charge a'condenser' 41 and"another'fb "ill` Y quency of thepoint's of the-picture.Av

to discharge'it withra timingoperated Yby heterodyne 38 synchronized through jappropriateV at aegee@ Each Ymbe operates only .during a lvjery shan ameland consequently J the condenser receives successive voltage- I steps having very accurate values in .durationrland amplitude. Damping devices VV42-and 431are provided to reducethe transition time between ea'ch'step.' r. .A

Thevideo smallband channel is mixed in'V 44 with then Y Yend Yof linesign'al 22and .endV ofjpicture signal 23fand also'a special signal-on wire v19 to identify upon arrival the numeral Yof the fieldr in the'grou'p of teneldsb Further identification VmeansV are required 'for` correct colorY transmission.`

Ar`In order VtoY layY a 'groundworkfor' explanation of Fig- Y ure 14, I `willgive another explanation of Figure 9, Yin

. 'the'.light of explanatoryv Figure 16.V

j Figure 9Y shows Yhow is made the distributionfofithe successive impulse -arriving inthe common Ychannel 59,7`

into a multiplicity Vof independent-channels V85, 86etc. Y

f synchronizing Vpulses of dilerentform fon amplitude Y Y are generally sent also in the same channel (namely the' end of line signals). The cadency .ofthis signal is F. i

After separation, these VsignalsV are' used in the channel 60 to synchronize a multiplicity vof oscillators 61, 62AY having frequency KlF/KgFhaving F as common YVbasic frequency. 'These oscillators generate'voltages in phase;V

and in phase quadrature. Namely oscillator V61 after amplicatio'ng'furnished the line 63 with phase voltages, and line 64 with phase quadrature voltages, at frequency KIF. Y

In the same manner. oscillator. 62 generatesin linel 65- Y voltageswinY phase and lineV 6 6-voltages in phase quadra? threat-frequency F2.V 'The four-phase and quadratureV voltagesY are fed to the Yprimaryfof four transformersV having a great number-of independent secondary'V wind-V ings. Y

l The number ofi-turns of the transformer secondary windings are in accordance with the amplitude and phase to' be obtained in eachV coil 66. l

n According to my prior V Patent;2,471,753'I obtain in a number of terminals 66Y 661` surges of voltage succcssivelyappearingin course of time. f

The successive surges of, voltage are isolated respectively for Vthepositive surgerby means of rectifier 67 and.

resistor 69 Van'dlfor,the`r`1egative surge by means Vofrecrtifier 678'and resistor 70.V l Y Y Y Y Y With an appropriatel choice Vof the phasea'nd-amplitudeV of theV different individual sinusoidal voltages atVV terminalV 66 it is'V possible to phase Vshift-the positive' surge Y and the negative surge so that the time between: the twoV` Y surges is anappropriate-.fraction of the recurrence period each channel.` n particular vcase where K1, K2 are odd numbers becauseeorfj the i 'symmetry of the curve, the negative surge and therposi- Y tive one .'arerat a time delay of Y A Y T The positive surge Yis used.' through .the means ofc'ondenser 71 andY resistor 73 and the. negative surge is used'-y Vthrough means of condenser-7 2 and resistor 73 The amplitude of the surges are shaped to an'accurate valuevbymeans of a voltage drop in resistor-V74.

f The-pesitiye Vsurge is limited. throughfmeans Vof yaY polarizedrectiiier '7775, and the negative surge is shapedby the means of a'second polarized rectifier 76.r Y

nel 84 leading to `a group'of'magneticrecordersfr` f negative pulses arefused for the discharge ofeondenser 83. @In fthe same mannen the other terminals`66 Vof the Ycir- Y uitwithin the dotted frame are usedtol operate thelother channelfas 85 L. which Vare l00.in Fig-l2;`

The Y pulses arriving through"Y terminals gV 66 e etc. :being Y( time phase shifted.V one Ywith another'the successive signals..Vv arriving from the jcommon channel v59 aredistributedfin etc.. 'if As it is illustrated,: tw'ojrindependent leads'vofgthe"comeV plex voltage distribution (dotted frame)VV as 66 andj66' inrv .o the casexofFigure, 9 are used simultaneously;for.thek ac-J.,

tuin toA eachfindividual channel84.k 85

tivation ofthe same independent channel-84.1V .Y

,ThisfpermitstoV-choose the Ashifting hetwceni'thez c Y* ldu'ctioliof charge and the:Y discharge at a value ,dilerent` from .I

Namely it permits the use of symmetrical compleirvoltage curves to obtain a 'duration forlstoring'rthe chargein the' Vcondenser that-is only afraction smaller Ythan T; n The explanation of this improvement of the vinvention Y appearsonFi'gure 22;'.V v e Y h'The symmetrical complex voltage ,ofterminalY 66 is shown in 500 with a positive surge voltagef501, '5071"k and a negative surge' of .voltage VV502 disposed'in the middle and* sponding to the l NV e' 5th o terminal in idot and hatched'line in terminal 66'. V *Y o The positive surge is 507 and the negative 508 for this terminal.

. The time Tl/VF corresponds-'to the distance between two successive'surges of same direction of the complex'- curve namely the distance between 501and'501.V` Y

YVWhen thesame complex curve( is used for the storingof 17. Y' signal in the capacityY (namely surge 501)`and for .the discharge (namelyV surge 502)'` the time ofmaintainingA the charge in the condenser is'only v Y VmV `isused. Y 1 l ,In order, to distribute betweenflOO channels the signals.

Thereforeon resistory 74 quasi rectangular pulses ofYV very accurate value appear successively. i Y

The positive pulse is used for. introducing (storing) the first signal in condenser 83 and theindividual first chan-` VYBut, according to the Ypresentiniprovement one uses" simultaneously a positive surge as505 and a negtiversurge as 508 corresponding'to `thelocation of a terminal' 66 1. `Vequalto i 'f theduration of the storing is increased tothetcitalflineV YT less a `small fraction. a Y Y Another feature of theV invention further'providesV ia rst distributionfrom theV common video channel into 10Q` independent recorders for each.frame'and a second distribution for 6 successive frames whenrthe three 'dot' system' coming from the common video channelait ispreferred .L to use-Va double stage of distribution shown'in' Figi, 14. o A rst step sloperated betWeen'lO independent inter-V 13 -r'nediatefchannelsfaud 'theneach 'intermediate channel is successivelyl 'divided' into 20 final channels. f .@lThe first stage of distribution-betweenw` channels is made in accordance with my Patent 2,471,253 that is the repartitionv between the 10 vchannels. numbered 1611, v. 16110 in l According to the inventionone uses for'the second stage (5fdistribution a pulse generator 1S6"'successively positive for the storing and negative for the discharge as explained in Figure 9 and explanation Fig. 18. Thelrnvention provides two groups of conductors 7 and .157 of 10 in Veach group with signals that are phase shifted from one group to 4the other, and Ywhich are used alternatively-foreach of the 2 groups. Y LAccording tomy patents, condensers 1061,` 10611, arc 10611, are provided on each of'10 lchannels of the rst distribution. i

v VThese condensers have for etect to prolong the action of the signal in the individual intermediate channel 161 at each time there are several conductors in which the voltage Ais in course of changing because of the first step commutator and the second distribution'can not be operated simultaneously for all the intermediate channels.

V`:According to the invention, vthe second step dstribution is made-alternatively on the odd'group of five channels in the 10 channels 1611, 1613, etc. and alternatively on the even group of 5 in 1612, 161,1, etc.

1 According to the invention, the second stage distributor is alternately operative on the lrst group through the impulses arriving via 157 and on the second group through the impulses arriving via 157'; the operation is very accuratelyV operative because Vat the time of the second stage repartition the 5 intermediate conductors definitely have the correct voltage stored in condensers 106. The switching in the primary distributor takes place while the other 5 intermediate channels are not in use.

AvAs explained in Figure 14, the storing of condenser 103115 obtained through the means of rectifier 104 and the discharge is obtained before the end of time T at appropriate timing through the means of impulses coming from generator 156 through the means of azsecond rectifier 105. These two operations follow in alternate order. Y.

According to Figure 14 this process has also an adtional advantage, as it has been explained in Figure 9. It is diicult to obtain in the independent channel as 84, 85, etc. voltages that have a stabilized value by comparison with ground.

1n order to provide in Fig. 9 the equivalent of a common conductor for 84 and 85 and etc., lprovide a high frequency type of coupling.

VAccording to the invention, Figure 14 the voltages stored inthe 100 condensers 10311, 10321, etc., are used for ymodulating a high frequency supply of power. This power is obtained from a common heterodyne 160, a common transformer and .a multiplicity of independent secondary windings. Each secondary 107 generates a high frequency constant voltage.

This voltage is introduced in series with the video intelligence voltages distributed in 100 individual condensers 1031 with a rectifier 108 in series: lt is the well known process for modulation of a carrying wave.

The choice of the most appropriate carrying wave for the magnetic recorder is about 60,000 per second.

The modulated wave passes through 100 transformers 109 which isolate the 100 output circuits which can be grounded or connected together on conductor 170.

The secondary of these transformers 109 feed simultaneously the grid control of three tubes 1001 1103 connected to independent recorder 1631 of the groups. The plate of only one tube out of 3 receives at each time the voltage and consequently only one is operative at any time. The choice of the plate is it. accordance with the order of the explorated frame, as explained in Figure 10 and ll.

v#{Ihe fs'arne disposition is"'realizedin alli fwotlierforiodd g'riitipsf` fed withv the same intermediate "channel "1611.

And all the evengroups 163111V toflig'are similarlyactiva'ted as shownin Fi VV141" ji* i" "e i 1 i The-- plates l1102x110L Y1510'11j-arerespectively-llinked tommagnetic recorders-181,1182,183,184, 185,186 in total r-number of 300-for the-3 points-system inthree separate groups operated on dite'rentportionslof'the reco'rding cylinder length.- it

A commutator 1901s used' for selectively controlling the three groups by Vsuccessively applying the plate voltage to each groupfrom battery 195.7Sectors 191, 192, 1.93 are connected toytheterminalsof each group of rec'ortiers.4 Y .The commutator Vis drivenby a motor synchronized on the third of field frequency, so that the tirst'eld is recorded on the reordersJconnected to 191, and the second field is recordedthrough sector 192, etc.N

p =T he commutation circuit in Fig.- 14 shows forA simplicity of description only 3-sectors for recording 3 fields of a single complete frame in rinelresolution.v Actually, the recording is followedv by reading the' picture intelligence and therefore a spacing leads to have va'commutator having sixv sectors instead of three,and a lnumber of reading devices and individual connectionsequal to the number of recorders.A In the three point system, the total number of magnetic heads and circuits is twice 300 that is 600; which allows to record an image on a portion of the cylinder and simultaneously readV and erase the preceding image on `another portion of-the cylinder which are used alternately to that effect.

Fig.. l5-shows the commutator in the case of the 5 point system with 10 sectors. l

The system of commutation in each group of recorders includes a small multipolar motor 112, synchronized Withithe end of frame signal, drives a group of 10 brushes on l0 fixed sectors, disposed at equal angleone with another.

Nine of these brushes are simultaneously connected to the negative terminal of biasing battery 115, and only one brush is at the positive voltage and activates a re-l corder. The others are rendered inoperative by the biasing`bru`shes.

"On the same axis of this small synchronized motor brush 111 is driven on a 2 sector commutator to obtain the voltage in conductors 165,1 and 165A' which are used respectively for the alternate recording of 2 complete pic- 4tures and the reading cf the record.

Figure 16 shows in a live dot system the means with ten wires 1201 120111 to successively feed the two conductors 88-89 and to obtain the order of sampling shown in Figures l0 and ll.

A delay line is used with a variable number of units, corresponding to the shifting of the dot of each horizontal line.

Each channel feeds one of the control grids of tube 147 withtwo control grids and all the plates are connected in parallel. Normally all of the second grids are normally negatively biased and consequently all of the tubes are locked. Y

Each of these tubes are unlocked in turn through the mens of a voltage introduced in series with the second gri The wiresfeeding these different grids are numbered 1591 1595 and 159s 159111. In a form of the invention they are connected to the tommutator described in Figure l5, or to electronic switching means for high frequency commutation. i

Figures I7 and 5 refer to an improvement of the invention vin which the scanning is automatically made of different size in accordance with the fact that the light intensity of the dot sampled is varying or not in the course of time.

ln Figure l7 it is shown in 200 the video voltage obtained from the electronic camera when the image of the subject is not varying that is when the subject is practically non moving.

Y curves 201, 202, 203, etc. f

Vnil and consequently "the 1 llt is shown in 2011-, 202fintdotted'linethe Vvalue ofthe videovoltage when the subject is moving and 'therefore `the light intensity of each dot is varying. u. t' Y I In Figure 17, the Y2 n5l-10` first points of the are supposed to remainjconst'ant but on the contrary it is supposed that dots, 111th tof25th'in the lineare vary- Ying in the vcourse of time in correspondence with the When the picture is ,not moving, the operation of Vcutting into pieces the signalsabove explained Vin `connection i `yvi`thfh`igure13 have'for eect to give inrcourse of the picture tive successive .frameY scanning, signals that are shownin M1, M2, M3,YM;1,' MY5., On Ytheiigu're appears the order of the dotto bescannedsuccessively as explained in FigurelO. Y 'I Y Theordinates kof each signalV areequal tothe same'of i curve 200 as shown at the lowerjleft part of-rFig. 17.'v Dur ying all theutime the picture is not moving thepverange of Vsignals are repeating without change.Y ,u

On the contrary, Vwhen the object Yis Vchanging-,and the light intensity of dot varies, the signals are-variable in,

amplitudei Curves N1, N2, N3, N4', N5 shows that the ordinate of each of the signals are equal to thesamefof, dotted lines 201, 202, 203 etc.

' t According to the improvement ofV the lvinvention, the ,change `of the light density is automatically evidenced from the comparison of amplitude ,of the signals at each sampling of any dot, and which ,correspondstoa .displacel Vmentofthe subject.

The ordinates M1 are consequently compared to N1 etc. 1

Figure 17shows the curveA of corresponding. to thefsub- Y stractiontM1-N1.V On thelO rst points on thegleftrA of the figure there is no displacement, the differencesfare nil.

They appearat thellth dot, at the 12th dot etc.V if The difference M1,-N1, is shown in,204,et'c. Vwhileth'e l dilerence M11-'N5 is shown in 206 etc.

When this difference, is nil, the slow comes from the recorder into play.YAY .v l Y If, the difference is not'nil (positive or negative), above a certain value the high, speed coarse ,scanningis autorate ne scanning u, In Figure l7, the fivelahst lines of the figure showsat Y 204. the result, of: this operation. `This rstcoarsesc'anning is preferably applied Vto 2 dots before and 2 dots after the'dotrsampled incourse of scanning; inthe ligure it isapplied toithe 4 following dots. i Y Y Thesame description is applicable to the scanning of the following frames, where'the coarse scanningis maintained as long as the difference M-'N is not quite Consequently: g Y, Y The ordinate Nz'is extended'to the Y4 points 207',"

The ordinate Nais extended tothe 4 points 205 The ordinate N4 is extended to the 4 points 208' ,'Ihe ordinate'NS is extended to. ther4poirnts 206 Y vx And so on;

Y' The Vsame argument isV applicable to, the following i scannings; the differences 209,210, 211,212,213 are not scanning ,is ,continuously Y ofV C.0arSetyPe-, ',But at/the timeY where thedilerence: becomes about nil (as in the case of 214) the line type of scanning-isiuged again instead ,of thez-fcoarse; A,'1`heordin'at`e's 'N1,",N`3,N5, N1; N, are simultaneously/used to reconstruct the succes- Vsivedots of 4thelpi'ctureas:shown inthebrolten line 2170,

220,221, 222, 22,3v corres'po`ndingY to theY respective ordinate of the curves 2 00, 2,01, 202'successively used.Y

Y Consequently the-passage from the tine scanning to the Y coarse scanningris Vautomatically made ,when therdirerV "ence is of a substantial value, vand the returnV tof the tine scanning is obtained automaticallyass'oon asV the differ;`

enceis lower than Ya small value.

,According toY the invention, this process. gives'conse Y Vquen'tly aV picture veryraccurate in time,-but mid-dlngfin Vresolution wheny the v-picture is moving, and u contrarily Y a very fine picture withY accurateV details butfretarded in ,time by about 1/srtuh of a secondrwhen the subject is pracf ticallyHnon-movingand' the density of thepoints non: ,Y

changing. Therefore in allcases the utilizationpffthe of Opportunity to the Spectator. Fig. 5 shows a simplified 'circuit to obtain plained in :the above described Figure lilllfli v5 point transmission of the video intelligence Y gives ,the maximum system. Y f Y corcler throughamplilier 399 (see Figure 3B).1

Channel -389vrarrives through the coaxialcable orf-like, Vfrom thesending station. 'Y Y V1 Y n u Y The twolnsigualsV on wires 388 and 389 are continuously comparedone with another `in order to ,evidence Vithe importance of the changing ,of the picture, and, are --ap-` plied to tubes Yand 91; The Vplate Vof these-tubes Vare connected` toA resistor 9701K and 91R.v These resistors ,are adjustable-'isoV as Yto vcompensate the. differencek of j thercharacteristics Ydata lof .tubes if there are some.` u

,The drop, of,Y voltage through Vthese two'resistors are compared one withthe other. Y, If no voltage appears ,be-

tween the plates of tubes 90 and,k 91,-1itmeans that the Vco1'-V respondingfpoints of the televisedV pictureI have 'maina tained 'substantiallyf the same value of. opacity. On the contrary, as aldierence ,of voltage,v appear's,the light Y density ofthe pointon the picture-has changed in the, course'of time'betwen the two 'scannings This change l Y may beV greater on vthe plate of tube 9,0or'f,a1ter'nativ`ely two channels.

on theV plate of tI'1b,e`,`9,1,,andV therefore the resulting volt-V t age maybe positive ornegative. However, by theme'an's of rectifier, A92, the potentialdifference `is rectified, and therefore is made to operate in the samedirection.V Y 1 Block 102 is Ythe ,final output circuit. Through this channel the signals of line,388 corresponding tothe,

video channel areartit'cially-reconstructed either` by using lthe signals of tive successive framesY simultaneously, ,or alternatively the signals of channel Y389 which corresponds to the coarse channel wherethe Vsame values Aof voltage 50' are applied to ve Vsuccessive points. n 1 To obtain this result, theplates, of tubes .100 and 101 are Yconnected in parallel. l These tubes-are the means for locking or unlocking .the ,transmission of fthe signalsL These tubes have each two'control grids.'l The modulated signals of channels 388 and`389are applied, for example, i

on the'control grid, and theY other grid is used iorlockingv and unlocking at appropriate time one or the votheroifthe Y This actionY ,is 1 commanded as, a 'Yfrunction of the voltageapplied to the condenser 93. "j Y, 1 A smallgdiiculty for obtaining thisrersult prevents the use of a common`re`turr`n wireand is overcome as'follows:

According to` this Vimprovement of the inventi voltages at theterrninals ofV condenser, V93 are applied -p tively tothe grid ofVV tube 100 and negatively-to i,

of tube 101.Y `To that effect heterodyne95 generates a highfrerquencyfcarrier Wave in-circuit 96 which iis rect- J fied by diode V97, andlhas its envelope-verifiedoi-,modulated` by theV the charge'on condenser 93;Y Battery 99 polarizes' the circuit to effectlthe desiredl sensitivity ofrresponse to changes in thecharge on condenser93.` AThe high fre-V 1 quency voltage so obtained reacts on-transformer ,98;

having two symmetricalr secondary'wi ndings. The volt-r,V age at the terminals l.of 'the two Asecondary ywindings are ,rectiied in opposite'directions,'and, dueto battery'B renders tube 100 conducting'whenever condenser the result Veirf Y ln this Aligurejthe 'channelV 88is coming fromY vthe re???Y 

